With respect to video coding, sub-pixel interpolation is used in various modern video codecs to increase motion compensation efficiency. Sub-pixel interpolation involves the use of a sub-pel filter to interpolate a reference picture to increase the inter-prediction accuracy. Experimental results show that well-designed long filters can achieve significant better coding efficiency compared with short filters. On the other hand, in a pipelined decoding system, a reference block is fetched and filtered for each inter-prediction block. Longer filters need extra pixels to be fetched each time and hence generally cause dramatic memory expansion.